Adds a new constructor for gfx::Image on iOS.

ios/chrome/browser/suggestions/image_fetcher_impl.mm

Index: ios/chrome/browser/suggestions/image_fetcher_impl.mm
diff --git a/ios/chrome/browser/suggestions/image_fetcher_impl.mm b/ios/chrome/browser/suggestions/image_fetcher_impl.mm
index 9920987f21e81c2894208e8a84235a93f8f93c63..7b56099c44a97040f0fa5a4a396b6852f54202e9 100644
--- a/ios/chrome/browser/suggestions/image_fetcher_impl.mm
+++ b/ios/chrome/browser/suggestions/image_fetcher_impl.mm
@@ -61,7 +61,7 @@ void ImageFetcherImpl::StartOrQueueNetworkRequest(
           // Most likely always returns 1x images.
           UIImage* ui_image = [UIImage imageWithData:data scale:1];
           if (ui_image) {
-            gfx::Image gfx_image(ui_image);
+            gfx::Image gfx_image(ui_image, base::scoped_policy::ASSUME);
             callback.Run(fetch_id, gfx_image);
             if (delegate_) {
               delegate_->OnImageFetched(fetch_id, gfx_image);